[time-nuts] One sure way to kill your FE-5680A or FE-5650A

Nick Sayer nsayer at kfu.com
Thu Jun 9 15:31:59 EDT 2016


> On Jun 9, 2016, at 10:11 AM, Bob Camp <kb8tq at n1k.org> wrote:
> 
> 
> One very real possibility is: The reason we *have* all these parts is that they
> have a bug in them, and were scrapped out  because of it.
> 

From what I’ve read elsewhere (and I can’t find a citation right now), they (at least the FE-5680As) were used in cell phone bases that were decommissioned after network upgrades.

> Bob
> 
> 
>> On Jun 9, 2016, at 8:03 AM, Clint Jay <cjaysharp at gmail.com> wrote:
>> 
>> It would seem so bit I don't remember seeing a 'reset'  chip in the 5680.
>> I'm wondering if there's scope to add one onto the rail that runs the PSD
>> and 80C320 to keep it in reset.
>> On 9 Jun 2016 13:00, "Bob Camp" <kb8tq at n1k.org> wrote:
>> 
>>> Hi
>>> 
>>> Based on the number of different ways there seem to be to corrupt the
>>> operating software
>>> in the FE Rb’s …. they seem to have a unique problem. There are a *lot* of
>>> devices
>>> using the same basic parts that don’t turn into a brick when this or that
>>> happens.
>>> 
>>> Bob
>>> 
>>>> On Jun 9, 2016, at 4:31 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>>>> 
>>>> 
>>>>> The ATTinys have brownout detectors in them that’s supposed to keep them
>>>>> from going bonkers during undervolt periods.
>>>> 
>>>> Startup and/or brownout has long been a nasty problem area for digital
>>>> designers.
>>>> 
>>>> In the old old days, there was typically a R/C delay on the reset pin to
>>> a
>>>> CPU.  That screwed up when the power supply ramped up slowly enough.
>>> Most
>>>> old timers have that merit badge.
>>>> 
>>>> Modern CPU chips often have specs like power must be OK for 200 ms before
>>>> releasing Reset.  Anything like that will have at least one corresponding
>>>> power monitor chip with several supply voltage inputs and the appropriate
>>>> delay.
>>>> 
>>>> The brownout side gets ugly when you look at the tolerances.  The
>>> tolerance
>>>> on the power monitor subtracts from the power supply tolerances.
>>>> 
>>>> There is another worm in the can.  How long does it take for your
>>> oscillator
>>>> to get going?
>>>> 
>>>> 
>>>> 
>>>> --
>>>> These are my opinions.  I hate spam.
>>>> 
>>>> 
>>>> 
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